Performed a router reboot this AM and when it came back up, all the ospf links on 172.16.x.x/30 were stuck on init. About 20 of them. Changed IP subnet to 10.0.x.x/30 and they came back up.
Logs did not provide any detail. I updated router to latest OS (just before 6.36 release) and same results.
Curious about what might explain that peculiar behavior and if anyone has seen it before.

Thanks for any insight.

Out of curiosity- did you try changing one of the links back? The IP range shouldn't matter at all as long as both ends agree on what net is being used...

Zerobyte
Not yet. It was really messing up the start of my customers business day so I kept it operational at the 10.0.x.x
I will be spending some more time on it this weekend and will give it a shot.
I agree the subnet should not matter. Just appeared to in this situation. In fact, I had 2 locations already on a 10.0.x.x and those continued to work while I made the changes to restore the network.

Could be that you have NAT rules on 172.16.x.x network? OSPF will stuck in init state if source address is changed by NAT.